Just what the Doctor ordered. 1977 280z

[240260280]

I'm sending Blue's intake with the block-off completed. It has a plug in the bottom and a plate on the top.

[madkaw]

1 hour ago, grannyknot said:

One of them has snapped off and it was already moving, I could turn it back and forth about a 1/4 turn, then it snapped

I would like to keep it just because it came with one but I may have to block it off, long way from that decision.

It really was a filthy job and the carbon and crap that came out of that heating chamber under the manifold, there was a pile of it.

1977 Color Wiring Diagram Version M.pdf

To continue on with what madkaw was asking, I'm realizing the EGR system is more elaborate than I first thought. The EGR controller at the end and moving toward the front next the BPT valve which is also heated by the same exhaust tube as the EGR, then vacuum tubes leading to the thermal vacuum valve that is on the end of the Idle Air Control Heater. If I do delete the EGR how much of the rest of the chain needs to be removed?

 

It’s funny you ask that. The 77 I’m doing still has everything there , so I plan on making it work, though I just found a broken piece on my thermal valve . Earlier models 9/76 the two tits were plastic instead of metal like yours. But other than that and all the rubber hoses being shot, I think I’ll try and make it work. It would be more work to eliminate everything at this point. Everything is pretty much tied together , so I don’t know what you can get away with as far as eliminating . My buddy has a 77 with all emissions in tact and it runs well. I think you would want to keep the AAR  for sure . The other point with mine is the 30k original miles motivates me to keep it stock

[siteunseen]

I kept the AAR.  EGR, BPT and the warming plate with the thermal switch were trashed.  I plugged the coolant lines to the warming plate and the hose on bottom of the throttle body that went to the BPT.  I'm pretty sure that's all I had to do.  You might be able to see in this picture?

[Captain Obvious]

15 hours ago, grannyknot said:

 If I do delete the EGR how much of the rest of the chain needs to be removed?

If you remove the EGR actuator at the end of the system, then all the rest of the stuff in between becomes teats on a boar.

The ONLY thing the TVV and BPT does is modulate the vacuum to the EGR actuator. So if there isn't any EGR actuator, then there's no need to modulate the vacuum to it and both the TVV and BPT devices become useless. You don't have to remove them, but there's no reason not to. Just plug the vacuum source on the throttle body, and if you remove the TVV, you'll have to plug the coolant hole where it used to be. Or you could leave the TVV in place just to keep the coolant from running out, but don't connect any vacuum lines to it.

Now, about the heating plate under the AAR... It also serves to heat the AAR itself, so it does serve a second function other than the EGR. But my PO had removed my heating plate, and I never really noticed any problems. Being in a cooler climate, you might find that your AAR will open up some and raise your idle even when you don't want it to do so, but where I am I did not have that problem.

[madkaw]

I knew I would learn a lot on this thread. The only thing broke that I found was the TVV valve which MSA had. I figured it was worth the 35$ and some new hoses to and see if the whole system works besides deleting everything . I don’t want to pull , plug , delete the EGR piping unless i can get nothing to work. I’ve been studying the FSM, , but didn’t read about how the TVV warmed the AAR, interesting . 

 

[Captain Obvious]

I'm not sure if there was a misunderstanding or not, but just to be clear...

The TVV does not heat the AAR.. Hot coolant heats the plate under the AAR. The same plate into which the TVV is installed. So the COOLANT heats both the AAR and TVV and the Issue being if you remove that entire plate as part of a "TVV delete" then you will lose your external AAR heating as well.

Now the AAR is also INTERNALLY heated, so depending on how cold it is where you live, the internal heating may be enough and you may not miss the external heat source at all. That is what happened in my case, but in Canada, it might be a different story.

[madkaw]

I understand that the coolant does not flow thru the AAR, but warms the plate the AAR sits on- that I didn’t know. I though the AAR was purely signal based from the ECU , but I am still learning . 

[Zed Head]

2 hours ago, madkaw said:

I though the AAR was purely signal based from the ECU 

Fuel pump relay.  It gets power when the fuel pump gets power.   Learn, learn, learn....  Edit - but, apparently, the ECU grounds the circuit.  I'm still learning too.  Although, I have faint memories of some weirdness with the diagrams.  Can't remember the details.

I had my fuel pump on its own power once, no power through the relay it was bypassed, and my idle stayed high until I remembered to switch it back to relay power.  That was on a cold engine.

Edited July 3, 2018 by Zed Head

[Captain Obvious]

Actually... Inside the ECU, the pin connected to the AAR is just hard shorted to ground. So they have the connection AVAILABLE to the ECU if they ever wanted to use the ECU to control the AAR, but they do not use it like that. It's just shorted to ground inside the ECU.

So other than the fact that the ECU has to be plugged into the connector, there's no real interaction between the AAR and the ECU. Anytime the engine is cranking or running, the AAR will be internally heating.

The reason they also externally heat it with the coolant plate underneath is that the internal electrical heating may not be enough warmth to close the AAR on a very cold day. Like when the air flowing through it is also very cold.

[grannyknot]

8 hours ago, Captain Obvious said:

The reason they also externally heat it with the coolant plate underneath is that the internal electrical heating may not be enough warmth to close the AAR on a very cold day. Like when the air flowing through it is also very cold.

So the AAR is actuated by temperature  alone?  Once it is closed off by internal heating and/or coolant plate how does the engine get air at idle? I guess I'm assuming that the AAR is serving the same function as an IAC (idle air control)

[240260280]

Engine gets normal air from a small passage in the Throttle Body that bypasses the Throttle Plate. A small needle screw controls this amount of idle air.

The AAR just gives extra air when it is cold to give a faster idle.

 

Circa 2003: http://www.atlanticz.ca/zclub/techtips/aar/index.html

Additional heating of AAR with water helps ensure it does not open when doing short stop and go's on cool to cold days.  AAR is only needed when the engine is cold; so water temp is a good indicator,

 

 

Edited July 4, 2018 by 240260280

[Captain Obvious]

Yes, the AAR is actuated by temperature alone. Some of that temperature is internally generated with an electrical heating coil, and some of that temperature is externally applied by the coolant running through the heating plate under the AAR, but yes... temperature alone. The colder it is out, the longer it takes to warm up. No computer control, but it works.

And as Blue mentioned above, the "normal - once warmed up" idle air comes through a passage built into the throttle body. It's the large headed spring loaded screw on the throttle body. You can see it in the very very bottom left of this pic: